XL-build fails to throw floating point exception

[KineticTheory]

The dsxx_fpe_trap_2 unit test is failing for XL Release builds.

>>> Running:   
>>>          /scratch/users/kellyt/cdash/darwin/draco/Nightly_xlc++-power9xl-develop/Release/build/src/ds++/test/do_exception
>>>          2

- fpe_trap: This platform is supported.

- Case two: trying to evaluate sqrt(-1.0)...
  result = nan
Test Passes: Application ran to completion

Checking the generated output files...

Test Passes: Case 2 -> sqrt(-1.0) test case
Test Fails: Failed to catch SIGFPE (Invalid floating point operation)

I think we need to tell XL to to look for these types of floating-point errors so its behavior matches other compilers. Trying:

• -qflttrap Ref